1. Technical Field
The present invention relates to an airbag device that deploys an airbag and protects an occupant in case of vehicle collision. More particularly, the invention relates to an airbag device that is disposed inside an instrument panel of the vehicle and protects an occupant in a passenger seat.
2. Background Information
An airbag devices that deploy an airbag to protect an occupant in case of vehicle collision are known. The airbag device is typically mounted inside a steering wheel or an instrument panel and protects the driver or an occupant in the passenger seat. In order to ensure the protection of the driver etc., the airbag device may be also mounted on the side portion of a seat back or above a side door.
Such airbag devices typically have a common base structure that includes a retainer case containing a folded airbag or inflator and a sensor that detects the vehicle collision. Specifically, when the vehicle collision is detected by the sensor, an igniting agent located inside the inflator is ignited and a gas-generating agent located inside the inflator is burned. As a result, gas is expelled out from the inflator into the airbag which causes the airbag to be filled with the gas and deployed.
However, the deployment direction of the airbag or the sequence and timing of the deployment directions (referred to below as a “deployment state”) affect the restraining ability that is necessary to protect the occupant safely. In order to control such a deployment state of airbags, in conventional airbag devices, for example, the airbag may be folded in a particular manner and a special member that controls the deployment state of the airbag may be provided inside the airbag.
However, with such conventional means, it is difficult to form the cloth from which the airbag is made, thus the manufacturing process is also difficult. Alternatively, the method of folding the airbag may be complex and the airbag deployment state is often difficult to control to produce an optimum result.
Patent Document 1 suggests an airbag device having a structure in which an interference portion that interferes with the airbag deployment and an escape portion into which the airbag subjected to interference can escape are formed outside the airbag. With such a structure, as the airbag deploys, the airbag is released from the interference portion. The deployment state of the airbag can be controlled by adjusting the time from the beginning of the deployment until the airbag is released from the interference portion.
Patent Document 1: Japanese Laid-open Patent Application No. 2001-30863.
However, in the configuration disclosed in Patent Document 1, the reduction in injury value is insufficient for occupants such as a child that is out of position or a woman of small stature. For example, when a child is abnormally close to the instrument panel, the inflated airbag deploys along the windshield, passes above the child's (occupant's) head and cannot demonstrate a sufficient restraining force. Further, when an occupant of small stature (e.g., a woman) is in the passenger seat, the inflated airbag directly contacts the occupant's head and sufficient restraining force cannot be achieved.